Regulation of type 1 fimbrial expression in uropathogenic <i>Escherichia coli</i> : heterogeneity of expression through sequence changes in the <i>fim</i> switch region

Leathart, Julian; Gally, David L.

doi:10.1046/j.1365-2958.1998.00802.x

Cited by 38 publications

(30 citation statements)

References 29 publications

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“…PCR and restriction digestion analysis of the fim switch (Leathart & Gally, 1998) from the E. coli CFT073-derived strains was carried out with [ 32 P]dATP to increase the sensitivity with which the fim switch in the on orientation could be detected. The constructs were grown under conditions considered to optimize Pap expression (Evans et al, 1980), which consistently resulted in low levels of type 1 fimbrial expression.…”

Section: Resultsmentioning

confidence: 99%

“…The number of blue and white colonies was counted, and the frequency calculated as a function of the number of generations that the original colony had been through, and was expressed as a value per cell per generation. Orientation of the fim switch was carried out essentially as described in Leathart & Gally (1998). fim DNA was amplified by PCR using primers 2535 and 3137, incorporating 7?4610 5 Bq [ 32 P]dATP for radiolabelling when necessary.…”

Section: Methodsmentioning

confidence: 99%

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Demonstration of regulatory cross-talk between P fimbriae and type 1 fimbriae in uropathogenic Escherichia coli

et al. 2006

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The majority of Escherichia coli strains isolated from urinary tract infections have the potential to express multiple fimbriae. Two of the most common fimbrial adhesins are type 1 fimbriae and pyelonephritis-associated pili (Pap). Previous research has shown that induced, plasmid-based expression of a Pap regulator, papB, and its close homologues can prevent inversion of the fim switch controlling the expression of type 1 fimbriae. The aim of the present study was to determine if this cross-regulation occurs when PapB is expressed from its native promoter in the chromosome of E. coli K-12 and clinical isolates. The regulation was examined in three ways: (1) mutated alleles of the pap regulatory region, including papB and papI, that maintain the pap promoter in either the off or the on phase were exchanged into the chromosome of both E. coli K-12 and the clinical isolate E. coli CFT073, and the effect on type 1 fimbrial expression was measured; (2) type 1 fimbrial expression was determined using a novel fimS : : gfp + reporter system in mutants of the clinical isolate E. coli 536 in which combinations of complete fimbrial clusters had been deleted; (3) type 1 fimbrial expression was determined in a range of clinical isolates and compared with both the number of P clusters and their expression. All three approaches demonstrated that P expression represses type 1 fimbrial expression. Using a number of novel genetic approaches, this work extends the initial finding that PapB inhibits FimB recombination to the impact of this regulation in clinical isolates. INTRODUCTIONUrinary tract infections (UTIs) are common, affecting a large proportion of the population. It is estimated that 20 % of women develop a UTI in their lifetime, and antibiotic treatment results in approximately 110 000 prescriptions per million inhabitants per annum in Europe (Naber, 2000). Escherichia coli strains are the predominant cause of uncomplicated UTIs, responsible for between 60 and 80 % of the cases reported in the UK each year (Graham & Galloway, 2001). Many infections are asymptomatic, especially in the elderly (Nicolle, 2001), but others result in cystitis. If the infection ascends to the kidney, then pyelonephritis can occur. Such infections are a significant origin of Gramnegative sepsis.Fimbrial adhesins are important virulence factors that allow binding of the bacteria to specific receptors on epithelial cells of the urinary tract. The two adhesins most commonly associated with UTI are type 1 fimbriae, and pyelonephritisassociated pili (Pap) and Pap-related fimbriae (Prf); the last two are collectively termed P fimbriae in this study. Type 1 fimbriae mediate binding to a-D-mannose-containing receptors and extracellular matrix components, whereas P fimbriae bind to glycoreceptors containing the aGal(1-4)bGal moiety (Lindberg et al., 1984). Although type 1 fimbriae are common to the majority of E. coli isolates, the FimH adhesin has been shown to be important in a mouse model of UTI, and a degranulation response to the fimbriae is asso...

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Demonstration of regulatory cross-talk between P fimbriae and type 1 fimbriae in uropathogenic Escherichia coli

et al. 2006

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“…Another possible mechanism for the differences observed between the cystitis and pyelonephritis strains in invertibleelement switching can be found in the differences observed in the sequence in and around the invertible element of several E. coli strains (26). The sequence changes were observed in areas where the FimB, FimE, and other accessory proteins (IHF, LRP, and H-NS) are believed to bind.…”

Section: Discussionmentioning

confidence: 99%

In Vivo Dynamics of Type 1 Fimbria Regulation in Uropathogenic Escherichia coli during Experimental Urinary Tract Infection

et al. 2001

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Escherichia coli is the primary cause of uncomplicated infections of the urinary tract including cystitis. More serious infections, characterized as acute pyelonephritis, can also develop. Type 1 fimbriae of E. coli contribute to virulence in the urinary tract; however, only recently has the expression of the type 1 fimbriae been investigated in vivo using molecular techniques. Transcription of type 1 fimbrial genes is controlled by a promoter that resides on a 314-bp invertible element capable of two orientations. One places the promoter in the ON orientation, allowing for transcription; the other places the promoter in the OFF orientation, preventing transcription. A PCR-based assay was developed to measure the orientation of the invertible element during an experimental urinary tract infection in mice. Using this assay, it was found that the percentage of the population ON in urine samples correlated with the respective CFU per gram of bladder (P ‫؍‬ 0.0006) but not with CFU per gram of kidney (P > 0.069). Cystitis isolates present in the urine of mice during the course of infection had a higher percentage of their invertible elements in the ON orientation than did pyelonephritis isolates (85 and 34%, respectively, at 24 h; P < 0.0001). In general, cystitis isolates, unlike pyelonephritis isolates, were more likely to maintain their invertible elements in the ON orientation for the entire period of infection. E. coli cells expressing type 1 fimbriae, expelled in urine, were shown by scanning electron microscopy to be densely packed on the surface of uroepithelial cells. These results suggest that expression of type 1 fimbriae is more critical for cystitis strains than for pyelonephritis strains in the early stages of an infection during bladder colonization.

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“…Orientation of the fim switch was carried out as described previously (23,33,45). Briefly, PCR was used to amplify a 603-bp region that incorporates the invertible fimA promoter element.…”

Section: Methodsmentioning

confidence: 99%

Pathogenic Potential of Emergent Sorbitol-Fermenting Escherichia coli O157:NM

et al. 2008

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Non-sorbitol-fermenting (NSF) Escherichia coli O157:H7 is the primary Shiga toxin-producing E. coli (STEC) serotype associated with human infection. Since 1988, sorbitol-fermenting (SF) STEC O157:NM strains have emerged and have been associated with a higher incidence of progression to hemolytic-uremic syndrome (HUS) than NSF STEC O157:H7. This study investigated bacterial factors that may account for the increased pathogenic potential of SF STEC O157:NM. While no evidence of toxin or toxin expression differences between the two O157 groups was found, the SF STEC O157:NM strains adhered at significantly higher levels to a human colonic cell line. Under the conditions tested, curli were shown to be the main factor responsible for the increased adherence to Caco-2 cells. Notably, 52 of 66 (79%) European SF STEC O157:NM strains tested bound Congo red at 37 C and this correlated with curli expression. In a subset of strains, curli expression was due to increased expression from the csgBAC promoter that was not always a consequence of increased csgD expression. The capacity of SF STEC O157:NM strains to express curli at 37 C may have relevance to the epidemiology of human infections as curliated strains could promote higher levels of colonization and inflammation in the human intestine. In turn, this could lead to increased toxin exposure and an increased likelihood of progression to HUS.

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Regulation of type 1 fimbrial expression in uropathogenic Escherichia coli : heterogeneity of expression through sequence changes in the fim switch region

Cited by 38 publications

References 29 publications

Demonstration of regulatory cross-talk between P fimbriae and type 1 fimbriae in uropathogenic Escherichia coli

Demonstration of regulatory cross-talk between P fimbriae and type 1 fimbriae in uropathogenic Escherichia coli

In Vivo Dynamics of Type 1 Fimbria Regulation in Uropathogenic Escherichia coli during Experimental Urinary Tract Infection

Pathogenic Potential of Emergent Sorbitol-Fermenting Escherichia coli O157:NM

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